Many powered systems in motorized vehicles are controlled by permanent magnet electric motors. Examples include window lifts, sunroofs, sliding van doors, vehicle trunks, tailgates, and seat and seat back recliners and adjusters. The variability of certain parameters in many powered systems (e.g., the supply voltage, operating temperature, and the load driven by the motor) produces a variable speed vs. torque performance characteristic in the permanent magnetic electric motor used to power such a system, leading to undesirable variation in the powered systems' travel time, noise level, and sealing force. A control method and system is needed for optimizing the speed vs. torque performance characteristic of motors that drive powered systems in motor vehicles notwithstanding the variability of operating parameters in these systems.